Hundreds marched peacefully through central Athens in a tribute to 15-year old Alexandros Grigoropoulos who was shot dead in 2008.
Some of the protesters set garbage containers on fire and set cars alight.
Earlier, people laid flowers and lit candles during a memorial service on the spot where Grigoropoulos was killed.
Police had deployed more than 2,000 officers in Athens.
Some in full riot gear formed protective cordons outside parliament and hotels in the city, while a helicopter hovered over the central Syntagma Square and neighbouring districts through the day.
Around noon, hundreds of students marched towards parliament.
On the night of Dec. 6, 2008, hours after Grigoropoulos was shot, thousands took to the streets of Athens, torching cars and smashing window shops and looting.
The riots, which were also fuelled by anger over unemployment and economic hardship in a prelude to Greece's debt crisis, lasted for weeks. (Reporting by Renee Maltezou, Costas Baltas and Lefteris Papadimas; Editing by Alison Williams)
(This story has not been edited by Devdiscourse staff and is auto-generated from a syndicated feed.)